Re: [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic_switching"

From: Dominik Brodowski
Date: Fri Jul 14 2017 - 03:01:49 EST

On Thu, Jul 13, 2017 at 06:19:53PM +0200, Rafael J. Wysocki wrote:
> On Thu, Jul 13, 2017 at 7:40 AM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> > There is no limitation in the ondemand or conservative governors which
> > disallow the transition_latency to be greater than 10 ms.
> >
> > The max_transition_latency field is rather used to disallow automatic
> > dynamic frequency switching for platforms which didn't wanted these
> > governors to run.
> >
> > Replace max_transition_latency with a boolean (dynamic_switching) and
> > check for transition_latency == CPUFREQ_ETERNAL along with that. This
> > makes it pretty straight forward to read/understand now.
> Well, using CPUFREQ_ETERNAL for that on the driver side is still not
> particularly straightforward IMO, so maybe add a
> "no_dynamic_switching" to the driver structure and set it to "true"
> for the one driver in question?

IIRC it's not just one driver which sets the latency to CPUFREQ_ETERNAL, and
where dynamic switching might be harmful or at least lead to undefined